Copyright Pipe Fabrication Institute
Provided by IHS under license with PFI
No reproduction or networking permitted without license from IHS
PFI Standard ES-7
(Revised September 2004)
CHARTER MEMBERS
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MINIMUM LENGTH AND SPACING
FOR WELDED NOZZLES
Prepared by
Pipe Fabrication Institute Engineering Committee
All PFI Standards are advisory only. There is no
agreement to adhere to any PFI Standard and their
use by anyone is entirely voluntary.
Copyright by
A current index of the latest revised ES Standards, Technical Bulletins and Safety Training Guideline is available from
the Pipe Fabrication Institute.
PFI Safety Training Guideline, Standards and Technical Bulletins are published to serve proven needs of the pipe
fabricating industry at the design level and in actual shop operations. Hence, such needs are continually considered and
reviewed by the Engineering Committee of the Pipe Fabrication Institute to provide recommended procedures, which
have been demonstrated by collective experiences to fulfill requirements in a manner for Code compliance. However,
as the PFI Standards are for minimum requirements the designer or fabricator always has the option of specifying
supplementary conditions in the form of requirements beyond the scope of the PFI publications.
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the Pipe Fabrication Industry
Since 1913
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PFI Standard ES-7
(Revised September 2004)
MINIMUM LENGTH AND SPACING FOR WELDED NOZZLES
MINIMUM RECOMMENDED DIMENSIONS FOR FIGURE 1
NOMINAL
Conversion
inches to millimeter
1. Scope
1.1 This Standard covers the minimum recommended
length, distance from open end on run, and
spacing dimensions of adjacent welded nozzles.
2. Nozzles without Saddles or
Reinforcement
2.1 Dimensions recommended for nozzles without
saddles or reinforcements are as shown in Fig. l
and Table l.
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3. Nozzles with Reinforcing Saddles or
Rings
3.1 Dimensions recommended for nozzles with saddles
or rings are as shown in Fig. 2 and Table 2.
4. Nozzles – Integrally Reinforced
4.1 Dimensions recommended for integrally
reinforced nozzles are as shown in Fig. 3 and
Table 3. These dimensions do not apply to
integrally reinforced insert butt weld nozzles.
5. Design Considerations
5.1 Certain materials and combinations of nozzle and
header pipe size and wall thickness together with
multiple branch openings welded to a header may
result in distortion of the header pipe. The
elimination or reduction of such distortion is
beyond the scope of this Standard.
5.2 All nozzle welds should be checked for
compliance with the applicable Code
requirements.
Factor
25.4
5.3 It is preferred that multiple branch openings
of in-line nozzles be spaced so that their
reinforcement zones do not overlap. If closer
spacing is necessary, the reinforcement
requirements of the applicable construction
Code shall be met.
5.4 Some configurations of integrally reinforced
nozzles in combination with certain header
sizes may present a problem in the
radiographic examination of the attachment
weld due to inability to meet the geometric
unsharpness requirements of the construction
Code.
5.5 Where attachments such as flanges, fittings,
valves and pipe insulation are involved,
minimum dimensions tabulated may have to
be increased to allow for required clearances.
5.6 In special cases, it may be possible to reduce
the dimensions given in the tabulation. Such
design should then be submitted to the
fabricator for individual consideration, as
close spacing may involve additional shop
operations to prevent, or correct distortion.
5.7 Integrally reinforced nozzles are considered
to be the commercially available types.
5.8 In cases of different nozzle diameters,
dimension "C", (Fig. & Tables 1 thru 3)
should be determined on the basis of the larger
of the two adjacent nozzles. For some nozzle
sizes, the recommended minimum spacing in
the tables may result in overlapping
reinforcement zones.
2-1/2
3
4
5
6
8
10
12
14
16
18
20
24
CENTER OF NOZZLE
TO END OF RUN
“A”
in.
(mm)
4-1/2
5
6
7
8
10
12
14
15
17
19
21
24
(114)
(127)
(152)
(178)
(203)
(254)
(305)
(356)
(381)
(432)
(483)
(533)
(610)
O.D. OF RUN TO END
OF NOZZLE
“B”
in.
(mm)
3
3-1/2
4
4-1/2
5
6
7
8
8-1/2
9
10
11
12
( 76)
( 89)
(102)
(114)
(127)
(152)
(178)
(203)
(216)
(229)
(254)
(279)
(305)
NOZZLES WITHOUT
SADDLES OR RING REINFORCEMENT
O.D. TO O.D. OF
NOZZLE
“C”
in.
(mm)
3
3-1/2
4
4-1/2
5
6
7
8
8-1/2
9
10
11
12
A
( 76)
( 89)
(102)
(114)
(127)
(152)
(178)
(203)
(216)
(229)
(254)
(279)
(305)
C
B
PIPE SIZE
OF NOZZLE
(in)
FIGURE 1
TABLE 1
MINIMUM RECOMMENDED DIMENSIONS FOR FIGURE 2
NOMINAL
PIPE SIZE
OF NOZZLE
(in)
2-1/2
3
4
5
6
8
10
12
14
16
18
20
24
CENTER OF NOZZLE
TO END OF RUN
“A”
in.
(mm)
6
7
8
9-1/2
11
14
17
20
22
25
28
31
36
(152)
(178)
(203)
(241)
(279)
(356)
(432)
(508)
(559)
(635)
(711)
(787)
(914)
O.D. OF RUN TO END
OF NOZZLE
“B”
in.
(mm)
4-1/2
5
5-1/2
6
6-1/2
8
9-1/2
11
12
13
14
15
16
(114)
(127)
(140)
(152)
(165)
(203)
(241)
(279)
(305)
(330)
(356)
(381)
(406)
O.D. TO O.D. OF
NOZZLE
“C”*
in.
(mm)
6
7
8
9-1/2
11
14
17
20
22
25
28
31
36
(152)
(178)
(203)
(241)
(279)
(356)
(432)
(508)
(559)
(635)
(711)
(787)
(914)
NOZZLES WITH
REINFORCING SADDLES OR RINGS
A
C
B
METRIC CONVERSIONS
The conversion of quantities between systems of units involves a determination of the number of significant digits to be
retained. All conversions depend upon the intended precision of the original and are rounded to the appropriate accuracy.
Pipe sizes together with applicable wall thicknesses are not shown with metric equivalents.
The SI (metric) values where included with the customary U. S. values in this Standard are the rounded equivalents of
the U. S. values and are for reference only.
Metric units were derived utilizing the following conversion factor:
FIGURE 2
TABLE 2
MINIMUM RECOMMENDED DIMENSIONS FOR FIGURE 3
NOMINAL
PIPE SIZE
OF NOZZLE
(in)
2-1/2
3
4
5
6
8
10
12
14
16
18
20
24
CENTER OF NOZZLE
TO END OF RUN
“A”
in.
(mm)
5-1/2
6
7
8
10
12
14
16
17
19
21
23
26
(140)
(152)
(178)
(203)
(254)
(305)
(356)
(406)
(432)
(483)
(533)
(584)
(660)
O.D. OF RUN TO END
OF NOZZLE
“B”
in.
(mm)
MANUFACTURER’S
STANDARDS
O.D. TO O.D. OF
NOZZLE
“C”*
in.
(mm)
3
3
3-1/2
4
5
6
7
8-1/2
9
10
11
12
14
( 76)
( 76)
( 89)
(102)
(127)
(152)
(178)
(216)
(229)
(254)
(279)
(305)
(356)
NOZZLES - INTEGRALLY REINFORCED
A
C
B
Copyright Pipe Fabrication Institute
Provided by IHS under license with PFI
No reproduction or networking permitted without license from IHS
PFI Standard ES-7
(Revised September 2004)
FIGURE 3
TABLE 3
*Minimum dimension “C” should be that tabulated for the larger of two adjacent nozzles.
Dimensions: Inches (Millimeters).
--`,,,,``````,,`,`,,,,``,`,```,,-`-`,,`,,`,`,,`---